Doc .DELETE_ON_ERROR.

Doc new MAKEFLAGS/MAKEOVERRIDES.
Doc .IGNORE/.SILENT with deps.

make.texinfo

@@ -10,8 +10,8 @@
 @set RCSID $Id$
 @set EDITION 0.47 DRAFT
 @set VERSION 3.72 Beta
-@set UPDATED 24 October 1994
-@set UPDATE-MONTH October 1994
+@set UPDATED 1 November 1994
+@set UPDATE-MONTH November 1994
 @set ISBN 1-882114-50-7
 
 @c finalout
@@ -2141,24 +2141,28 @@ match that file's name.
 @findex .IGNORE
 @item .IGNORE
 
-Simply by being mentioned as a target, @code{.IGNORE} says to ignore
-errors in execution of commands.  The dependencies and commands for
-@code{.IGNORE} are not meaningful.
+If you specify dependencies for @code{.IGNORE}, then @code{make} will
+ignore errors in execution of the commands run for those particular
+files.  The commands for @code{.IGNORE} are not meaningful.
 
-@samp{.IGNORE} exists for historical compatibility.  Since
-@code{.IGNORE} affects every command in the makefile, it is not very
-useful; we recommend you use the more selective ways to ignore errors
-in specific commands.  @xref{Errors, ,Errors in Commands}.
+If mentioned as a target with no dependencies, @code{.IGNORE} says to
+ignore errors in execution of commands for all files.  This usage of
+@samp{.IGNORE} is supported only for historical compatibility.  Since
+this affects every command in the makefile, it is not very useful; we
+recommend you use the more selective ways to ignore errors in specific
+commands.  @xref{Errors, ,Errors in Commands}.
 
 @findex .SILENT
 @item .SILENT
 
-Simply by being mentioned as a target, @code{.SILENT} says not to
-print commands before executing them.  The dependencies and commands
-for @code{.SILENT} are not meaningful.
+If you specify dependencies for @code{.SILENT}, then @code{make} will
+not the print commands to remake those particular files before executing
+them.  The commands for @code{.SILENT} are not meaningful.
 
-@samp{.SILENT} exists for historical compatibility.  We recommend you
-use the more selective ways to silence specific commands.
+If mentioned as a target with no dependencies, @code{.SILENT} says not
+to print any commands before executing them.  This usage of
+@samp{.SILENT} is supported only for historical compatibility.  We
+recommend you use the more selective ways to silence specific commands.
 @xref{Echoing, ,Command Echoing}.  If you want to silence all commands
 for a particular run of @code{make}, use the @samp{-s} or
 @w{@samp{--silent}} option (@pxref{Options Summary}).
@@ -2721,7 +2725,7 @@ actually doing them.
 The @samp{-s} or @samp{--silent}
 flag to @code{make} prevents all echoing, as if all commands
 started with @samp{@@}.  A rule in the makefile for the special target
-@code{.SILENT} has the same effect 
+@code{.SILENT} without dependencies has the same effect 
 (@pxref{Special Targets, ,Special Built-in Target Names}).
 @code{.SILENT} is essentially obsolete since @samp{@@} is more flexible.@refill
 
@@ -2910,10 +2914,10 @@ This causes @code{rm} to continue even if it is unable to remove a file.
 @cindex @code{--ignore-errors}
 @findex .IGNORE
 When you run @code{make} with the @samp{-i} or @samp{--ignore-errors}
-flag, errors are ignored in
-all commands of all rules.  A rule in the makefile for the special target
-@code{.IGNORE} has the same effect.  These ways of ignoring errors are
-obsolete because @samp{-} is more flexible.
+flag, errors are ignored in all commands of all rules.  A rule in the
+makefile for the special target @code{.IGNORE} has the same effect, if
+there are no dependencies.  These ways of ignoring errors are obsolete
+because @samp{-} is more flexible.
 
 When errors are to be ignored, because of either a @samp{-} or the
 @samp{-i} flag, @code{make} treats an error return just like success,
@@ -2926,6 +2930,7 @@ can any other that depends on it either directly or indirectly.  No further
 commands will be executed for these targets, since their preconditions
 have not been achieved.
 
+
 @cindex @code{-k}
 @cindex @code{--keep-going}
 Normally @code{make} gives up immediately in this circumstance, returning a
@@ -2947,11 +2952,28 @@ is why Emacs' @code{compile} command passes the @samp{-k} flag by
 default.
 @cindex Emacs (@code{M-x compile})
 
+@findex .DELETE_ON_ERROR
+@cindex deletion of target files
+@cindex removal of target files
+@cindex target, deleting on error
+Usually when a command fails, if it has changed the target file at all,
+the file is corrupted and cannot be used---or at least it is not
+completely updated.  Yet the file's timestamp says that it is now up to
+date, so the next time @code{make} runs, it will not try to update that
+file.  The situation is just the same as when the command is killed by a
+signal; @pxref{Interrupts}.  So generally the right thing to do is to
+delete the target file if the command fails after beginning to change
+the file.  @code{make} will do this if @code{.DELETE_ON_ERROR} appears
+as a target.  This is almost always what you want @code{make} to do, but
+it is not historical practice; so for compatibility, you must explicitly
+request it.
+
 @node Interrupts, Recursion, Errors, Commands
 @section Interrupting or Killing @code{make}
 @cindex interrupt
 @cindex signal
 @cindex deletion of target files
+@cindex removal of target files
 @cindex target, deleting on interrupt
 @cindex killing (interruption)
 
@@ -3042,28 +3064,6 @@ is @samp{cd subdir; /bin/make}.  If you use a special version of
 executed for recursive invocations.
 @cindex @code{cd} (shell command)
 
-Also, any arguments that define variable values are added to @code{MAKE},
-so the sub-@code{make} gets them too.  Thus, if you do @samp{make
-CFLAGS=-O}, so that all C compilations will be optimized, the
-sub-@code{make} is run with @samp{cd subdir; /bin/make CFLAGS=-O}.@refill
-
-@vindex MAKE_COMMAND
-@vindex MAKEOVERRIDES
-The @code{MAKE} variable actually just refers to two other variables
-which contain these special values.  In fact, @code{MAKE} is always
-defined as @samp{$(MAKE_COMMAND) $(MAKEOVERRIDES)}.  The variable
-@code{MAKE_COMMAND} is the file name with which @code{make} was invoked
-(such as @file{/bin/make}, above).  The variable @code{MAKEOVERRIDES}
-contains definitions for the variables defined on the command line; in
-the above example, its value is @samp{CFLAGS=-O}.  If you @emph{do not}
-want these variable definitions done in all recursive @code{make}
-invocations, you can redefine the @code{MAKEOVERRIDES} variable to
-remove them.  You do this in any of the normal ways for defining
-variables: in a makefile (@pxref{Setting, ,Setting Variables}); on the command
-line with an argument like @samp{MAKEOVERRIDES=} 
-(@pxref{Overriding, ,Overriding Variables}); or with an environment variable
-(@pxref{Environment, ,Variables from the Environment}).
-
 As a special feature, using the variable @code{MAKE} in the commands of
 a rule alters the effects of the @samp{-t} (@samp{--touch}), @samp{-n}
 (@samp{--just-print}), or @samp{-q} (@w{@samp{--question}}) option.
@@ -3106,9 +3106,9 @@ commands, is propagated to the subsystem.@refill
 Variable values of the top-level @code{make} can be passed to the
 sub-@code{make} through the environment by explicit request.  These
 variables are defined in the sub-@code{make} as defaults, but do not
-override what is specified in the sub-@code{make}'s makefile unless
-you use the @samp{-e} switch
-(@pxref{Options Summary, ,Summary of Options}).@refill
+override what is specified in the makefile used by the sub-@code{make}
+makefile unless you use the @samp{-e} switch (@pxref{Options Summary,
+,Summary of Options}).@refill
 
 To pass down, or @dfn{export}, a variable, @code{make} adds the variable
 and its value to the environment for running each command.  The
@@ -3126,6 +3126,15 @@ The special variables @code{SHELL} and @code{MAKEFLAGS} are always
 exported (unless you unexport them).
 @code{MAKEFILES} is exported if you set it to anything.
 
+@code{make} automatically passes down variable values that were defined
+on the command line, by putting them in the @code{MAKEFLAGS} variable.
+@iftex
+See the next section.
+@end iftext
+@ifinfo
+@xref{Options/Recursion}.
+@end ifinfo
+
 Variables are @emph{not} normally passed down if they were created by
 default by @code{make} (@pxref{Implicit Variables, ,Variables Used by
 Implicit Rules}).  The sub-@code{make} will define these for
@@ -3274,6 +3283,15 @@ in its environment.  In response, it takes the flags from that value and
 processes them as if they had been given as arguments.
 @xref{Options Summary, ,Summary of Options}.
 
+@cindex command line variable definitions, and recursion
+@cindex variables, command line, and recursion
+@cindex recursion, and command line variable definitions
+Likewise variables defined on the command line are passed to the
+sub-@code{make} through @code{MAKEFLAGS}.  Words in the value of
+@code{MAKEFLAGS} that contain @samp{=}, @code{make} treats as variable
+definitions just as if they appeared on the command line.
+@xref{Overriding, ,Overriding Variables}.
+
 @cindex @code{-C}, and recursion
 @cindex @code{-f}, and recursion
 @cindex @code{-I}, and recursion
@@ -3323,13 +3341,39 @@ subsystem:
         cd subdir; $(MAKE) MAKEFLAGS=
 @end example
 
+@vindex MAKEOVERRIDES
+The command line variable definitions really appear in the variable
+@code{MAKEOVERRIDES}, and @code{MAKEFLAGS} contains a reference to this
+variable.  If you do want to pass flags down normally, but don't want to
+pass down the command line variable definitions, you can reset
+@code{MAKEOVERRIDES} to empty, like this:
+
+@example
+MAKEOVERRIDES =
+@end example
+
+@noindent
+@cindex Arg list too long
+@cindex E2BIG
+This is not usually useful to do.  However, some systems have a small
+fixed limit on the size of the environment, and putting so much
+information in into the value of @code{MAKEFLAGS} can exceed it.
+If you see the error message @samp{Arg list too long}, this may be the problem.
+@findex .POSIX
+@cindex POSIX.2
+(For strict compliance with POSIX.2, changing @code{MAKEOVERRIDES} does
+not affect @code{MAKEFLAGS} if the special target @samp{.POSIX} appears
+in the makefile.  You probably do not care about this.)
+
 @vindex MFLAGS
-A similar variable @code{MFLAGS} exists also, for historical compatibility.
-It has the same value as @code{MAKEFLAGS} except that it always begins with
-a hyphen unless it is empty (@code{MAKEFLAGS} begins with a hyphen only when
-it begins with an option that has no single-letter version, such as
-@samp{--warn-undefined-variables}).  @code{MFLAGS} was traditionally used
-explicitly in the recursive @code{make} command, like this:
+A similar variable @code{MFLAGS} exists also, for historical
+compatibility.  It has the same value as @code{MAKEFLAGS} except that it
+does not contain the command line variable definitions, and it always
+begins with a hyphen unless it is empty (@code{MAKEFLAGS} begins with a
+hyphen only when it begins with an option that has no single-letter
+version, such as @samp{--warn-undefined-variables}).  @code{MFLAGS} was
+traditionally used explicitly in the recursive @code{make} command, like
+this:
 
 @example
 subsystem: